1. Field of the Invention
This invention relates to a Ni-based alloy excellent in intergranular corrosion resistance, stress corrosion cracking resistance, mechanical strength and hot workability, and more particularly, this invention relates to a Ni-based, Cr-containing alloy excellent in intergranular stress corrosion resistance in high-temperature water.
2. Description of the Prior Art
It is described in "Corrosion", Vol. 24, No. 3, p. 55 (1968) that Inconel Alloy 600 (hereinafter referred to briefly as Alloy 600) has stress corrosion cracking susceptibility in high-temperature pure water, which can not be eliminated even when the C content is reduced to 0.02%, and even Ti and Nb for fixing C are not effective in controlling the stress corrosion cracking susceptibility. However, the C content of 0.02% is too high for a Ni-based alloy essentially having a low content of dissolved carbon to be effective in preventing intergranular sensitivity, and the contents of Ti and Nb for fixing carbon are too low for the alloy to be effective in fixing carbon. The intergranular sensitivity can be completely controlled by reducing the carbon content to less than 0.010% or by adding larger amounts of Nb and Ti. However, the carbon content of as low as below 0.010% will bring about a drawback that the mechanical strength is lowered and the yield strength at 0.2% elongation is lowered to below 25 kg/mm.sup.2, which is the specification for Alloy 600, while the addition of Nb and Ti in larger amounts will raise the cost and decrease the rate of production.